{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"c219d29e313edd724523cb318cb64eff2261668ef508489fb46163459af4ef72","created":"2026-10-03T07:17:57Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"4e5923e181ea9a897682f20666aa3289954bd556475f4a4aad45ca3489c27901","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"bio.chromatin-extrusion.mitotic-chromosome-formation","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Before division, each long chromosome is packed within minutes into a compact rod. Motors called condensins form loops around a helical axis, and whether loop formation alone explains the rod's shape, stiffness and the separation of the two copies is not settled.","posed_since":"","precise":"Hi-C time courses support nested condensin II and condensin I loops arranged around a helical scaffold (Gibcus and co-workers, 2018). Determine whether a polymer model with measured condensin extrusion rates, densities and loop sizes, and no added crosslinks, reproduces mitotic Hi-C maps, the compaction ratio, the stretching elasticity of isolated chromatids, and sister-chromatid resolution together with topoisomerase II activity.","problem_ref":null,"references":"","settled_by":"Parameter-free polymer simulation compared with Hi-C, imaging and micromechanical measurements of mitotic chromosomes under condensin and topoisomerase II depletion.","status_note":"The helical loop architecture was reported in 2018 (Science, doi 10.1126/science.aao6135); a quantitative account of chromosome mechanics from extrusion alone is not established, to this survey's knowledge.","title":"Does loop extrusion alone build and stiffen mitotic 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